Method for manufacturing SiC substrate

Abstract

A method for manufacturing an SiC substrate includes: performing a CMP treatment on an SiC substrate; after the CMP treatment, capturing an image of a surface of the SiC substrate to detect a scratch; determining the SiC substrate as a good article when a length L of the scratch having a contrast value equal to or larger than a threshold value is not more than π(D/2)2/A×F/100, wherein the scratch having the contrast value equal to or larger than the threshold value in the image serves as a starting point of an epitaxial defect, a diameter of the SiC substrate is represented by D, a length of a long side of a device chip to be formed on the SiC substrate is represented by A, and an allowable defective rate caused by scratches is represented by F.

The invention claimed is: 
     
       1. A method for manufacturing an SiC substrate comprising:
 performing a CMP treatment on an SiC substrate; 
 after the CMP treatment, capturing an image of a surface of the SiC substrate to detect a scratch; 
 determining the SiC substrate as a good article when a length L of the scratch having a contrast value equal to or larger than a threshold value is not more than π(D/2) 2 /A×F/100, 
 wherein the scratch having the contrast value equal to or larger than the threshold value in the image serves as a starting point of an epitaxial defect, 
 a diameter of the SiC substrate is represented by D, 
 a length of a long side of a device chip to be formed on the SiC substrate is represented by A, and 
 an allowable defective rate caused by scratches is represented by F. 
 
     
     
       2. The method for manufacturing an SiC substrate according to  claim 1 , wherein the CMP treatment and the scratch detection are repeated until the SiC substrate is determined as a good article. 
     
     
       3. The method for manufacturing an SiC substrate according to  claim 1 , further comprising epitaxially growing an SiC film on the SiC substrate determined as a good article. 
     
     
       4. The method for manufacturing an SiC substrate according to  claim 2 , further comprising epitaxially growing an SiC film on the SiC substrate determined as a good article.